Leonard Leslie Snelling was born in Stockwell, Surrey, South London, in 1871. [The birth of Leonard Leslie Snelling was registered in the district of Lambeth during the 2nd Quarter of 1871]. Leonard Snelling was the son of Charlotte and Frederick Snelling, a builder from Kent. In the early 1880s, Leonard was living with his parents and five siblings in Lambeth, but after his father, Frederick Snelling, died in 1886, at the age of 45, his widowed mother decided to take her family to Bexhill-on-Sea.
By 1892, Leonard Snelling had established a photographic portrait studio at 3, Albert Road, Bexhill-on-Sea.
In 1901, Leonard Leslie Snelling married Edith Charlotte Bassett (born 1874, Croydon, Surrey), the daughter of Naomi and Henry Alexander Bassett, a builder of Croydon.
In 1901, Leonard Snelling was recorded as a photographer at 5, Hambro Road, Natal Road, Streatham.
Leonard Leslie Snelling died at Kingston-on-Thames in 1938.